No organ parting required, but the F&F (in which you get Frame, Fork, seatpost and headset) isn't the cheapest, but the attention to detail is pretty good.

The ONLY* carbon, drop bar, double disc road bike that can take full fenders, and full internal routing (either cable or hydraulic brake lines) for A$2,395 that is available. NOW. There are a few others available, but NONE that have this complete list of goodies.

It is reasonably easy to boil the fluid on a real-world production car if you do a few hot laps at a race circuit. If we're going to talk real-world conditions, try a few reasonably hard stops in your car and watch the pedal feel change.

But that really is beside the point. From what I understand it is possible to heat your discs up enough that they can boil the fluid and make the brakes fade. While dot4 fluid has a fairly high boiling point (446 deg celcius), it absorbs fluid so the boiling point does decrease in real world conditions. It's a phenomenon that is acknowledged to occur on mountainbikes. So I am curious as to if and how it is dealt with on road bikes.

I imagine we would put a fair deal of stress on a disc brake on an extended downhill, and to be honest I'm not sure if I'd rather risk blowing a tyre or losing my brakes all together due to fade. If I could pick I'd probably say lets blow the rear tyre up, haha!

On the whole I think it's a technology that will become fairly mainstream but with the riding I do (lots of climbing [and descending] fairly steep stuff) I'm not going to be an early adopter.

There are disadvantages of disc brakes which appear to have been glossed over in the frenzy to embrace this new offering on a road bike. The torsional braking forces put more stress on the spokes which will require more of them and also of thicker gauge (offsetting some of the weight savings from not needing an alloy braking surface). Beefier forks will also be needed (again, adding weight). The rear wheel will be weaker due to the need for dishing on both sides.

It is reasonably easy to boil the fluid on a real-world production car if you do a few hot laps at a race circuit. If we're going to talk real-world conditions, try a few reasonably hard stops in your car and watch the pedal feel change.

But that really is beside the point. From what I understand it is possible to heat your discs up enough that they can boil the fluid and make the brakes fade. While dot4 fluid has a fairly high boiling point (446 deg celcius), it absorbs fluid so the boiling point does decrease in real world conditions. It's a phenomenon that is acknowledged to occur on mountainbikes. So I am curious as to if and how it is dealt with on road bikes.

I imagine we would put a fair deal of stress on a disc brake on an extended downhill, and to be honest I'm not sure if I'd rather risk blowing a tyre or losing my brakes all together due to fade. If I could pick I'd probably say lets blow the rear tyre up, haha!

On the whole I think it's a technology that will become fairly mainstream but with the riding I do (lots of climbing [and descending] fairly steep stuff) I'm not going to be an early adopter.

The change in pedal feel will have more to do with the pad material being outside of the optimum operating limits.

It is rare for even a race car to boil it's fluid, and that is with massive rotors glowing red/orange hot and dissapating a lot more energy than a road car can even try to.

Granted, it can still happen, but I'd say it's rare.

Will it happen on a road bike - in my experience (13,000+km), you'd have to be trying hard to do it.

biker jk wrote:There are disadvantages of disc brakes which appear to have been glossed over in the frenzy to embrace this new offering on a road bike. The torsional braking forces put more stress on the spokes which will require more of them and also of thicker gauge (offsetting some of the weight savings from not needing an alloy braking surface). Beefier forks will also be needed (again, adding weight). The rear wheel will be weaker due to the need for dishing on both sides.

And then offset by some other weight savings.

From my Volagi, the 57cm frame is 1,225g, and this has full internal cable routing, clever little plates to make it neater as well which adds to the weight, so not bad. The fork is 482g with 380mm of uncut steerer tube.

Overall, those weights are 200 or so grams over a reasobnably light frame, but I'm not going to compare with a VWD Cervelo, as that is a completely different frame.

My wheelset, using 29er carbon rims (24mm wide) with 28 spokes front and 32 rear comes to 1,421g which is not bad.

Overall the bike will shave in just under 8kg, and for a bike with some mid tier parts, is pretty damn good for a double disc road bike.

LOL forgot all about that one... boiled brake fluid equals ZERO brakes. That just doesn't happen unless you failed to bleed properly, or you've got ancient fluid. My experience is that you can have much older fluid than the recommended 2 year life span as well without issues

I just don't see the system having these kinds of problems unless people are seriously underprepared to actually ride their bike as per the technology. There are limits to everything. Brakes will fade. Tubes will blow off... perhaps people should do some work checking their limits before bombing down epic descents

boss wrote:What are the benefits of hydro over cable? And are there issues with boiling the fluid on hydraulic setups?

Hydro typically has better 'feel' than cable. Cable discs feel very similar in application to rim brakes since it is essentially the same clamping mechanism as rim brakes. In my experience, well set-up hydro brakes have longer service intervals than cable brakes. But there are always buts....

The two biggest griefs that roadies shifting to discs are going to have to come to terms with is disc squeal and bleeding. Your brakes will squeal and turkey gobble if you don't bed the discs and pads in just so. And the bleeding of hydraulic lines can be a black art compared to the ease with which most cable brakes can be tweaked.

It's possible to boil the hydraulic fluid (certainly happens in the MTB world) but on the road it would only likely occur if you do something incredibly mad such as descending from Mt. William in the Grampians like a speed obsessed loon and finding yourself repeatedly responding to oncoming traffic....

boss wrote:It is reasonably easy to boil the fluid on a real-world production car if you do a few hot laps at a race circuit. If we're going to talk real-world conditions, try a few reasonably hard stops in your car and watch the pedal feel change.

The change in pedal feel will have more to do with the pad material being outside of the optimum operating limits.

It is rare for even a race car to boil it's fluid, and that is with massive rotors glowing red/orange hot and dissapating a lot more energy than a road car can even try to.

Granted, it can still happen, but I'd say it's rare.

+1

There's two ways for a car's brake system to fail due to heat.

If the pedal goes soft and you can push it to the floor with negligible braking effect, that's because your incompressible brake fluid has gone compressible - it has boiled. It happens, but it's uncommon.

If the pedal stays hard but you have to use more and more pedal force to get the braking effect you want, that's because the friction level of the pads has reduced. That's brake fade.

More robust friction materials are more resistant to fade than lower performing materials.

If somebody's hydraulic brakes were to get seriously cooked, I would expect them to experience a hard pedal (or level) with decreasing brake effectiveness, right up until the fluid boils and their levers suddenly go right to the bar.

Boiled fluid is like a snapped brake cable. It's not like progressively "losing your brakes" on a long hill.

boss wrote:I imagine we would put a fair deal of stress on a disc brake on an extended downhill, and to be honest I'm not sure if I'd rather risk blowing a tyre or losing my brakes all together due to fade. If I could pick I'd probably say lets blow the rear tyre up, haha!

If you have some water in your old fluid and you overheat it, then the levers go soft, they don't immediately go straight back to the bars and fail to work at all. ie you should have 1.5 brakes when you begin to boil one, not nil, and the bike should have sufficient braking power to get it down below the critical speeds and stop. For those that like to accelerate out of corners and brake for the next one, this is probably just not going to happen, its only going to happen to people that ride the brakes, and they'll feel the lever going softer.

barefoot wrote:Boiled fluid is like a snapped brake cable. It's not like progressively "losing your brakes" on a long hill.

tim

its not actually like that on a bike, because its a small amount of water that will boil first, and unless the bottom half of the line was all water (and mine aren't after 7 years!), then you get 1 bubble which can be fully compressed by the lever.